newbie questions (2) : Detect presence of plugin/ActiveX via PHP3? and Linked PHP scripts?

Hello, I'm just starting to learn php, so please forgive me if this is a retarded question, but I was wondering if it is possible to detect whether a plugin and/or ActiveX control is installed on a user's machine via php3 when they visit a site. I've crawled around the php manual and some 3rd party sites and found code that will parse the http user agent header and echo out code for particular browsers, http://www.phpbuilder.com/columns/tim20000821.php3 , but I haven't yet found any mention of detecting plugins/ActiveX controls on users' machines. Basically, I'd like to be able to find shockwave and flash players on a users computer and, if they exist, write out the proper html...and, if they aren't present, write out a different bit of html. I've been using client-side javascript (with some vbscript for msie win) to do this, but I was hoping that I could do it via php. Basically, I'm tired of having to toss in huge script blocks with clods and clods of document.write statements. My second question is - is it possible to include php scripts in a page through some sort of linking, in a way analogous to how external javascripts can be included - ie <script type="text/javascript" src="crappyscript.js"></script>? Sorry for the dumb questions, but I'm just starting out with php. Much thanks for your help. brian donovan (remove "nocrap" from email) ICQ: 32895200